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https://issues.apache.org/jira/browse/JAMES-3626?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Benoit Tellier closed JAMES-3626.
---------------------------------
Resolution: Fixed
> Setting value of a collection inserts tomstone
> ----------------------------------------------
>
> Key: JAMES-3626
> URL: https://issues.apache.org/jira/browse/JAMES-3626
> Project: James Server
> Issue Type: Improvement
> Components: cassandra
> Affects Versions: master
> Reporter: Benoit Tellier
> Priority: Major
> Labels: cassandra, perf
> Fix For: 3.7.0
>
> Time Spent: 1h 40m
> Remaining Estimate: 0h
>
> https://docs.datastax.com/en/landing_page/doc/landing_page/dataModel.html#dataModel__checkTableStructure
> {code:java}
> Check use of collection types
> When insert or full update of a non-frozen collection occurs, such as
> replacing the value of the column with another value like UPDATE table SET
> field = new_value …, Cassandra inserts a tombstone marker to prevent possible
> overlap with previous data even if data did not previously exist. A large
> number of tombstones can significantly affect read performance.
> When you know that no previous data exists and to prevent creation of
> tombstones when inserting data into a set or map (or when performing the full
> update of a set or map), you can use append operation for columns. For
> example:
> CREATETABLE test.m1 (
> id int PRIMARY KEY,
> m map<int, text>
> );
> instead of using:
> INSERT INTO test.m1(id, m) VALUES (1, {1:'t1', 2:'t2'});
> or
> UPDATE test.m1 SET m = {1:'t1', 2:'t2'} WHERE id = 1;
> which generate tombstones, execute:
> UPDATE test.m1 SET m = m + {1:'t1', 2:'t2'} WHERE id = 1;
> which has the same result, but without tombstone generation.
> {code}
> Affected tables:
> - imapUidTable (use of a non frozen set for user flags)
> - inserts are done
> - full updates are done
> - This table is critical for JMAP performance. Not that it can explain
> the ~10% performance hit that occurs when reading mailbox with recent inserts
> versus reading mailboxes without recent inserts.
> - messageIdTable (use of a non frozen set for user flags)
> - inserts are done
> - full updates are done
> - This table is critical for IMAP performance.
> - enqueuedMailsV3 (non frozen list data types are mistakenly used for
> RECIPIENTS and PER_RECIPIENT_SPECIFIC_HEADERS - frozen would be acceptable -
> map is used for attributed and could be frozen too)
> - As a temporary measure, we can fix the inserts.
> - This table is critical to the browse start update performance
> - mailRepositoryContentV2 (non frozen list data types are mistakenly used
> for RECIPIENTS and PER_RECIPIENT_SPECIFIC_HEADERS - frozen would be
> acceptable- map is used for attributed and could be frozen too)
> - As a temporary measure, we can fix the inserts.
> - This table is not critical
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